Process for obtaining bornyl and isobornyl esters



, In this way the subsequent esterification is 1 Patented Dec. 15, 1931UNITED STATES LUDWIG SCHMIDT, or HAMBURG-BERGEDORF, GERMANY, ASSIGNOR TOSOGIETE ALSAOIENNE DE rnonorrs GHIMIQUES, or PARIS, FRANCE, A rnnncnCOMPANY PROCESS FOR OBTAINING BORNYL AND ISOBORNYL ESTERS No Drawing.Application filed August 20, 1928, Serial No. 300,949, and in FranceFebruary 18, 1928.

It is known that bornyl and isobornyl esters are obtained withsatisfactory technical outputs by heating at an ordinary pressure pineneor oils containing pinene with organic acids with the addition of mixedacig anhydride of boric acid and another aci According to the presentapplication it has been found that in this operation the ester contentcan be substantially increased by carrying out the condensation in twoseparate processes side by side, as follows:

(1) First of all, pinene or oils containing pinene are treated withmixed acid anhydride of boric acid and another acid, for instanceacetoboric anhydride, the latter either in the finished state or so tobe formed in situ, alone, i. e. without addition of the organic acid tobe esterified, for instance acetic acid. The quantity of the mixed acidanhydride of boric and other acid can vary within relatively wide.limits and this preesterification serves chiefly for the purpose ofobtaining as high a temperature as possible, for the purpose ofconverting the condensation agent i. e. the mixed anhydride of boric andother acid, into the condition which is most effective for thesubsequent esterification.

(2) When the desired maximum temperature is obtained, there then takesplace in the second operation the addition of the free organic acid,preferably in a measured excess, to the reaction mixture, which additiontakes place slowly while continuously heating.

cifected with the continuous action of the condensing agent, until amaximum ester content is reached. When this is reached,

the process is interrupted and it is found that the yield of ester,owing to the separate method of procedure is on an average 1 520% higherthan if the free organic acid were introduced into the process from theoutset.

This fact was not to be foreseen. In this case too boronyl andisoboronyl esters are obtained exclusively, without any formation ofresin.

The technical effect of the present process as compared with the knownprocess consists broadly in obtaining higher yields of ester. Forinstance the final outputs from 136 kgs. pinene plus 30 kgs. acetoboricanhydride and 100 kgs. glacial acetic, acid according to the knownprocess, that is to say in one single operation amount on an average to60% P T OFFICE.

at the end to 60-65%. The reactionproduct is treated with water, inwhich case the acetoboric anhydride decomposes into boric acid andacetic acid, while the bornyl and isobornyl acetate formed separates atthe top as an oily layer. Purification is then carried out in a knownmanner either by steam distillation or vacuum distillation, and thensaponification with alcoholic alkali, a mixture of pure bornyl andisobornyl acetate of melting point 196199 0. being formed.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is 1. In the process of obtaining bornyl andisobornyl esters by heating at an ordinary pressure pinene with analiphatic monocarboxylic acid with the addition of mixed acid anhydride.of boric acid and an aliphatic monocarboxylic acid, the feature thatthe esterification is effected in two stages the first stage beingefi'ected with the mixed acid anhydride of boric acid and an aliphaticmonocarboxylic acid, the esterifi-cation being thereupon completed bythe addition of free aliphatic monocarboxylic acid.

2. In the process of obtaining bornyl and isobornyl' esters by heatingat an ordinary pressure oils containing pinene with an aliphaticmonocarboxylic acid with the addition of mixed acid anhydride of boricacid and an aliphatic monocarboxylic acid, the

feature that the esterification is effected in two stages the firststage being effected With the mixed acid anhydride of boric acid and analiphatic monocarboxylic acid, the esteri- .fication being thereuponcompleted by the addition of free aliphatic monocarboxylic acid.

3. The process as claimed in claim 1 in which the mixed acid anhydrideof boric acid and an aliphatic monocarboxylic acid is formed in situ.

4. The process as claimed in claim 2 in which the mixed acid anhydrideof boric acid and an aliphatic monocarboxylic acid is formed in situ.

In testimony whereof I aflix my signature.

DR. LUDWIG SCHMIDT.

